This invention relates to a supporting ring for casting machines for concrete pipes for use in moulding the socket end of the pipe and as a base for the green pipe during the removal of the casting mould and at rate during the initial hardening process, said supporting ring consisting of an annular body comprising a lower flange, which projects laterally, for the moulding of the end face of the socket and a substantially plane top for moulding the end face of the pipe body inside to socket.